I mentioned complexity. One of the most extraordinary challenges to science in general – not just biological science – is this whole question of complexity. The laws of physics are true laws; they're what philosophers called nomothetic – the law... for instance, the laws of thermodynamics are hard to evade. The second law of thermodynamics is a gorgeous instance. But the question of whether there are laws in biology and above all laws in psychology, that have the same – oh, how shall I say – warrant or force is a debatable issue. But let's come back to Darwin because I think this is very important.

Darwin left a work unfinished; he knew that. We are in the challenge of trying to complete Darwin's program. We're trying to do it, even to the point of The Descent of Man and the origins of consciousness and the mechanisms, etc. I think there's a very important thing to say – whether you believe that there should be nomothetic principles in biology, orderly put, so it's like physics – and I think that is that you... you have to understand that there is a component of Darwinism that is truly extraordinary. It never really existed in the same sense in physics: and that is the idea of history. That what Darwin did is he introduced history into science. Now, not all of history as it's understood in the dictionary, but the idea that there are historical events that have immense consequences later on in terms of the outcome. This is the basis of many arguments about whether, if we had to begin all over again, would human beings emerge from evolution. The argument I think between [Stephen] Gould and several other what he calls Darwinian fundamentalists, right? Dawkins and people like that. In any event, I think you have to keep that in mind, but you also have to keep in mind that the laws of physics, being very general, also don't deal a lot of them, with very complex events, even in physics. This has been pointed out by a Nobel Laureate in Stanford, Robert Laughlin, who's a physicist who won the Nobel Prize I think in the field of superconductivity, that even in physics you have this kind of thing. And so the idea of the exhaustiveness of science comes up: can you in fact say that science is exhaustive? Can you have a theory of everything?

Well, as I see it so far, as an amateur, because now I'm looking at fields I'm no expert in; it seems to me that if you did have a theory of everything in physics, the only thing it would leave out is a physicist. That's perhaps not the best deal. So we do... we are now confronting certain kinds of limits to science – some of them parochial, some of them economic, but some of them really quite fundamental. The parochial and economic are obvious. If, for instance, in order to get to a certain distance called the Planck distance 10¯³³cm, you need to have two supercolliders a light year apart, you've had it. What are you going to do? If you have to have string theory with a billion billion billionth of the size of a proton, and you need energies just beyond all belief, are you going to settle for a theory that's mathematically complete but not in fact decidable one way or another by experiment? In biology we have... not quite so critical, but quite a serious situation and it comes as a result of our progress. Our progress has been immense in the fields of genetics and molecular biology. We have techniques to do all kinds of incredible things easily, so that people, for instance, can start right in the middle; they don't even have to have the fundamentals of molecular structure in their head. They have techniques and they can buy kits and they can do all kinds of things – sequencing molecules and what have you. And there's a plethora of data; it's an absolute inundation of what I see in the journals. More new journals, more pages in the journals, more data, data, data, data. But what's in common in all these cases is a surprising set of affairs – namely, things are not connected up as much as people would like them to be.